A wire is a single, usually cylindrical, string of metal. Wires are used to bear mechanical loads, to carry electricity and/or telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various wire gauges.

In the electrical and electronic field, vast quantities of aluminium, copper, nickel and steel wire are employed for telephone and data wires and cables, and as conductors in electric power transmission, and heating. The metals suitable for wire, possessing almost equal ductility, are platinum, silver, iron, copper, aluminium and gold. Special purpose wire is however made from other metals. For instance, the wire for light bulb and vacuum tube filaments is made by tungsten because of its high melting temperature. Copper wires are also plated with other metals, such as tin, nickel, and silver to handle different temperatures, provide lubrication, provide easier stripping of rubber from copper.